Fix NPE in suspension point in monitor call checker

#KT-27484 Fixed

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/checkers/SuspensionPointInSynchronizedCallChecker.kt

@@ -42,7 +42,8 @@ class SuspensionPointInSynchronizedCallChecker : CallChecker {
             if (parent !is KtValueArgumentList) {
                 child = parent
             }
-            parent = parent.parent
+            // parent.parent can be null if we edit the file, see EA-2158254 and KT-27484
+            parent = parent.parent ?: return
         }
     }
 

idea/idea-completion/testData/basic/multifile/SuspensionPointInMonitor/SuspensionPointInMonitor.kt

@@ -0,0 +1,13 @@
+inline val C.v: Int get() = 1
+class C {
+    fun f(block: suspend C.() -> Unit): Unit = TODO()
+}
+suspend fun yield() = {}
+fun f(c: C) {
+    c.f {
+        v.toString()
+        yie<caret>
+    }
+}
+
+// EXIST: yield

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/MultiFileJvmBasicCompletionTestGenerated.java

@@ -359,6 +359,11 @@ public class MultiFileJvmBasicCompletionTestGenerated extends AbstractMultiFileJ
         runTest("idea/idea-completion/testData/basic/multifile/StaticMembersOfNotImportedClassNameConflict/");
     }
 
+    @TestMetadata("SuspensionPointInMonitor")
+    public void testSuspensionPointInMonitor() throws Exception {
+        runTest("idea/idea-completion/testData/basic/multifile/SuspensionPointInMonitor/");
+    }
+
     @TestMetadata("SyntheticExtensionDeprecated")
     public void testSyntheticExtensionDeprecated() throws Exception {
         runTest("idea/idea-completion/testData/basic/multifile/SyntheticExtensionDeprecated/");