diff --git a/zap/src/main/java/org/zaproxy/zap/extension/script/ExtensionScript.java b/zap/src/main/java/org/zaproxy/zap/extension/script/ExtensionScript.java
index 5b006917429..7a35886c481 100644
--- a/zap/src/main/java/org/zaproxy/zap/extension/script/ExtensionScript.java
+++ b/zap/src/main/java/org/zaproxy/zap/extension/script/ExtensionScript.java
@@ -546,11 +546,17 @@ public ScriptTreeModel getTreeModel() {
      *
      * <p>The script is added to the tree of scripts and its scripts/templates loaded, if any.
      *
+     * <p>The call to this method has no effect if the given type or its name is null.
+     *
      * @param type the new type of script
      * @throws InvalidParameterException if a script type with same name is already registered
      * @see #removeScriptType(ScriptType)
      */
     public void registerScriptType(ScriptType type) {
+        if (type == null || type.getName() == null) {
+            return;
+        }
+
         if (typeMap.containsKey(type.getName())) {
             throw new InvalidParameterException("ScriptType already registered: " + type.getName());
         }
@@ -623,6 +629,10 @@ public void removeScripType(ScriptType type) {
      * @see #registerScriptType(ScriptType)
      */
     public void removeScriptType(ScriptType type) {
+        if (type == null || type.getName() == null) {
+            return;
+        }
+
         ScriptType scriptType = typeMap.remove(type.getName());
         if (scriptType != null) {
             getTreeModel().removeType(scriptType);
@@ -630,6 +640,9 @@ public void removeScriptType(ScriptType type) {
     }
 
     public ScriptType getScriptType(String name) {
+        if (name == null) {
+            return null;
+        }
         return this.typeMap.get(name);
     }
 
diff --git a/zap/src/main/java/org/zaproxy/zap/utils/Statistics.java b/zap/src/main/java/org/zaproxy/zap/utils/Statistics.java
index e838c3ed5fb..abd5eddf088 100644
--- a/zap/src/main/java/org/zaproxy/zap/utils/Statistics.java
+++ b/zap/src/main/java/org/zaproxy/zap/utils/Statistics.java
@@ -34,6 +34,10 @@ public void incCounter(String key) {
     }
 
     public void incCounter(String key, long inc) {
+        if (key == null) {
+            return;
+        }
+
         stats.compute(key, (k, v) -> (v != null ? v : 0) + inc);
     }
 
@@ -42,10 +46,18 @@ public void decCounter(String key) {
     }
 
     public void decCounter(String key, long dec) {
+        if (key == null) {
+            return;
+        }
+
         stats.compute(key, (k, v) -> (v != null ? v : 0) - dec);
     }
 
     public void setHighwaterMark(String key, long value) {
+        if (key == null) {
+            return;
+        }
+
         Long curValue = stats.get(key);
         if (curValue == null || value > curValue) {
             stats.put(key, value + 1);
@@ -53,6 +65,10 @@ public void setHighwaterMark(String key, long value) {
     }
 
     public void setLowwaterMark(String key, long value) {
+        if (key == null) {
+            return;
+        }
+
         Long curValue = stats.get(key);
         if (curValue == null || value < curValue) {
             stats.put(key, value + 1);
@@ -60,11 +76,19 @@ public void setLowwaterMark(String key, long value) {
     }
 
     public Long getStat(String key) {
+        if (key == null) {
+            return null;
+        }
+
         return stats.get(key);
     }
 
     public Map<String, Long> getStats(String keyPrefix) {
         Map<String, Long> map = new HashMap<>();
+        if (keyPrefix == null) {
+            return map;
+        }
+
         for (Entry<String, Long> stat : stats.entrySet()) {
             if (stat.getKey().startsWith(keyPrefix)) {
                 map.put(stat.getKey(), stat.getValue());
@@ -78,6 +102,10 @@ public void clearAll() {
     }
 
     public void clear(String keyPrefix) {
+        if (keyPrefix == null) {
+            return;
+        }
+
         Iterator<Entry<String, Long>> iter = stats.entrySet().iterator();
         while (iter.hasNext()) {
             Entry<String, Long> entry = iter.next();
diff --git a/zap/src/test/java/org/zaproxy/zap/extension/script/ExtensionScriptUnitTest.java b/zap/src/test/java/org/zaproxy/zap/extension/script/ExtensionScriptUnitTest.java
index f8e8f25fb53..0c91fcc1f90 100644
--- a/zap/src/test/java/org/zaproxy/zap/extension/script/ExtensionScriptUnitTest.java
+++ b/zap/src/test/java/org/zaproxy/zap/extension/script/ExtensionScriptUnitTest.java
@@ -64,6 +64,59 @@ void shouldReturnThreadSafeScriptTypesCollection() {
         assertDoesNotThrow(it::next);
     }
 
+    @Test
+    void shouldHandleRegistrationOfNullScriptType() {
+        // Given
+        ExtensionScript extensionScript = new ExtensionScript();
+        ScriptType scriptType = null;
+
+        // When / Then
+        assertDoesNotThrow(() -> extensionScript.registerScriptType(scriptType));
+    }
+
+    @Test
+    void shouldHandleRegistrationOfScriptTypeWithNullName() {
+        // Given
+        ExtensionScript extensionScript = new ExtensionScript();
+        ScriptType scriptType = new ScriptType(null, "i18n.type", null, false);
+
+        // When / Then
+        assertDoesNotThrow(() -> extensionScript.registerScriptType(scriptType));
+    }
+
+    @Test
+    void shouldHandleRemovalOfNullScriptType() {
+        // Given
+        ExtensionScript extensionScript = new ExtensionScript();
+        ScriptType scriptType = null;
+
+        // When / Then
+        assertDoesNotThrow(() -> extensionScript.removeScriptType(scriptType));
+    }
+
+    @Test
+    void shouldHandleRemovalOfScriptTypeWithNullName() {
+        // Given
+        ExtensionScript extensionScript = new ExtensionScript();
+        ScriptType scriptType = new ScriptType(null, "i18n.type", null, false);
+
+        // When / Then
+        assertDoesNotThrow(() -> extensionScript.removeScriptType(scriptType));
+    }
+
+    @Test
+    void shouldGetNullScriptTypeFromNullName() {
+        // Given
+        ExtensionScript extensionScript = new ExtensionScript();
+        String scriptTypeName = null;
+
+        // When
+        ScriptType type = extensionScript.getScriptType(scriptTypeName);
+
+        // Then
+        assertThat(type, is(nullValue()));
+    }
+
     @Test
     void shouldCreateScriptsCache() {
         // Given
diff --git a/zap/src/test/java/org/zaproxy/zap/utils/StatisticsUnitTest.java b/zap/src/test/java/org/zaproxy/zap/utils/StatisticsUnitTest.java
index 54c02983f43..e226981ab00 100644
--- a/zap/src/test/java/org/zaproxy/zap/utils/StatisticsUnitTest.java
+++ b/zap/src/test/java/org/zaproxy/zap/utils/StatisticsUnitTest.java
@@ -55,6 +55,16 @@ void shouldIncreaseCounter() throws Exception {
         assertThat(statistics.getStat(STAT_KEY), is(equalTo(1L)));
     }
 
+    @Test
+    void shouldIgnoreIncreaseCounterForNullKey() {
+        // Given
+        Statistics statistics = new Statistics();
+        // When
+        statistics.incCounter(null);
+        // Then
+        assertThat(statistics.getStat(null), is(nullValue()));
+    }
+
     @Test
     void shouldIncreaseExistingCounter() throws Exception {
         // Given
@@ -76,6 +86,16 @@ void shouldIncreaseCounterWithGivenValue() throws Exception {
         assertThat(statistics.getStat(STAT_KEY), is(equalTo(5L)));
     }
 
+    @Test
+    void shouldIgnoreIncreaseCounterWithGivenValueForNullKey() {
+        // Given
+        Statistics statistics = new Statistics();
+        // When
+        statistics.incCounter(null, 5);
+        // Then
+        assertThat(statistics.getStat(null), is(nullValue()));
+    }
+
     @Test
     void shouldIncreaseExistingCounterWithGivenValue() throws Exception {
         // Given
@@ -107,6 +127,16 @@ void shouldDecreaseCounter() throws Exception {
         assertThat(statistics.getStat(STAT_KEY), is(equalTo(-1L)));
     }
 
+    @Test
+    void shouldIgnoreDecreaseCounterForNullKey() {
+        // Given
+        Statistics statistics = new Statistics();
+        // When
+        statistics.decCounter(null);
+        // Then
+        assertThat(statistics.getStat(null), is(nullValue()));
+    }
+
     @Test
     void shouldDecreaseExistingCounter() throws Exception {
         // Given
@@ -128,6 +158,16 @@ void shouldDecreaseCounterWithGivenValue() throws Exception {
         assertThat(statistics.getStat(STAT_KEY), is(equalTo(-5L)));
     }
 
+    @Test
+    void shouldIgnoreDecreaseCounterWithGivenValueForNullKey() {
+        // Given
+        Statistics statistics = new Statistics();
+        // When
+        statistics.decCounter(null, 5);
+        // Then
+        assertThat(statistics.getStat(null), is(nullValue()));
+    }
+
     @Test
     void shouldDecreaseExistingCounterWithGivenValue() throws Exception {
         // Given
@@ -182,6 +222,19 @@ void shouldReturnNoStatsIfNoneWithGivenPrefix() throws Exception {
         assertThat(stats.size(), is(equalTo(0)));
     }
 
+    @Test
+    void shouldReturnNoStatsWithNullPrefix() {
+        // Given
+        Statistics statistics = new Statistics();
+        statistics.incCounter("other.stats.a");
+        statistics.incCounter("other.stats.b");
+        statistics.incCounter("other.stats.c");
+        // When
+        Map<String, Long> stats = statistics.getStats(null);
+        // Then
+        assertThat(stats.size(), is(equalTo(0)));
+    }
+
     @Test
     void shouldClearAllStats() throws Exception {
         // Given
@@ -213,4 +266,43 @@ void shouldClearStatsWithSamePrefix() throws Exception {
         assertThat(statistics.getStat("other.stats.a"), is(not(nullValue())));
         assertThat(statistics.getStat("other.stats.b"), is(not(nullValue())));
     }
+
+    @Test
+    void shouldIgnoreClearStatsWithNullPrefix() {
+        // Given
+        Statistics statistics = new Statistics();
+        statistics.incCounter("stats");
+        statistics.incCounter("stats.a");
+        statistics.incCounter("stats.b");
+        statistics.incCounter("other.stats.a");
+        statistics.incCounter("other.stats.b");
+        // When
+        statistics.clear(null);
+        // Then
+        assertThat(statistics.getStat("stats"), is(equalTo(1L)));
+        assertThat(statistics.getStat("stats.a"), is(equalTo(1L)));
+        assertThat(statistics.getStat("stats.b"), is(equalTo(1L)));
+        assertThat(statistics.getStat("other.stats.a"), is(equalTo(1L)));
+        assertThat(statistics.getStat("other.stats.b"), is(equalTo(1L)));
+    }
+
+    @Test
+    void shouldIgnoreSetHighwaterMarkForNullKey() {
+        // Given
+        Statistics statistics = new Statistics();
+        // When
+        statistics.setHighwaterMark(null, 10);
+        // Then
+        assertThat(statistics.getStat(null), is(nullValue()));
+    }
+
+    @Test
+    void shouldIgnoreSetLowwaterMarkForNullKey() {
+        // Given
+        Statistics statistics = new Statistics();
+        // When
+        statistics.setLowwaterMark(null, 10);
+        // Then
+        assertThat(statistics.getStat(null), is(nullValue()));
+    }
 }