"Suspicious ==/===": do not report when comparison with null is included

So #KT-24001 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/SuspiciousEqualsCombination.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.idea.inspections
 import com.intellij.codeInspection.LocalInspectionToolSession
 import com.intellij.codeInspection.ProblemHighlightType
 import com.intellij.codeInspection.ProblemsHolder
+import org.jetbrains.kotlin.idea.intentions.branchedTransformations.isNullExpression
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
 
@@ -29,12 +30,16 @@ class SuspiciousEqualsCombination : AbstractKotlinInspection() {
     private fun KtBinaryExpression.parseBinary(pair: ComparisonOperands = ComparisonOperands()): ComparisonOperands {
         when (operationToken) {
             KtTokens.EQEQ, KtTokens.EXCLEQ -> {
-                (left as? KtNameReferenceExpression)?.let(pair.eqEqOperands::add)
-                (right as? KtNameReferenceExpression)?.let(pair.eqEqOperands::add)
+                if (!left.isNullExpression() && !right.isNullExpression()) {
+                    (left as? KtNameReferenceExpression)?.let(pair.eqEqOperands::add)
+                    (right as? KtNameReferenceExpression)?.let(pair.eqEqOperands::add)
+                }
             }
             KtTokens.EQEQEQ, KtTokens.EXCLEQEQEQ -> {
-                (left as? KtNameReferenceExpression)?.let(pair.eqEqEqOperands::add)
-                (right as? KtNameReferenceExpression)?.let(pair.eqEqEqOperands::add)
+                if (!left.isNullExpression() && !right.isNullExpression()) {
+                    (left as? KtNameReferenceExpression)?.let(pair.eqEqEqOperands::add)
+                    (right as? KtNameReferenceExpression)?.let(pair.eqEqEqOperands::add)
+                }
             }
             KtTokens.ANDAND, KtTokens.OROR -> {
                 right?.parseExpression(pair)

idea/testData/inspections/suspiciousEqualsCombination/inspectionData/expected.xml

@@ -34,4 +34,13 @@
         <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Suspicious combination of == and ===</problem_class>
         <description>Suspicious combination of == and ===</description>
     </problem>
+
+    <problem>
+        <file>test.kt</file>
+        <line>18</line>
+        <module>light_idea_test_case</module>
+        <entry_point TYPE="file" FQNAME="test.kt" />
+        <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Suspicious combination of == and ===</problem_class>
+        <description>Suspicious combination of == and ===</description>
+    </problem>
 </problems>

idea/testData/inspections/suspiciousEqualsCombination/test.kt

@@ -7,6 +7,15 @@ object Main {
         if (type === CONST1 || type == CONST2 && !(type === CONST3)) return
         if (type === CONST1 || type1 == CONST2 && type === CONST3) return
         if (type === CONST1 || type1 == CONST1 && type === CONST3) return
+
+        val type2: Main? = null
+        if (type2 == null || type === type2) return
+
+        val type3: Main? = null
+        if (type3 === null || type == type3) return
+
+        val type4: Main? = null
+        if (type4 == null || type === type2 || type1 == type) return
     }
 
     val CONST1 = Main;