Nullability bug fix in the source code

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinCoreEnvironment.kt

@@ -313,8 +313,7 @@ public class KotlinCoreEnvironment private constructor(
 
         public fun disposeApplicationEnvironment() {
             synchronized (APPLICATION_LOCK) {
-                if (ourApplicationEnvironment == null) return
-                val environment = ourApplicationEnvironment
+                val environment = ourApplicationEnvironment ?: return
                 ourApplicationEnvironment = null
                 Disposer.dispose(environment.getParentDisposable())
             }

idea/tests/org/jetbrains/kotlin/idea/filters/AbstractKotlinExceptionFilterTest.kt

@@ -61,7 +61,7 @@ public abstract class AbstractKotlinExceptionFilterTest: KotlinCodeInsightTestCa
                 MOCK_LIBRARY_JAR = MockLibraryUtil.compileLibraryToJar(MOCK_LIBRARY_SOURCES, "mockLibrary", true)
             }
 
-            val mockLibraryJar = MOCK_LIBRARY_JAR
+            val mockLibraryJar = MOCK_LIBRARY_JAR ?: throw AssertionError("Mock library JAR is null")
             val mockLibraryPath = FileUtilRt.toSystemIndependentName(mockLibraryJar.canonicalPath)
             val libRootUrl = "jar://$mockLibraryPath!/"