[FIR] Fix NPE on empty throws

^KT-60325 fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java

@@ -321,6 +321,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
             runTest("compiler/testData/diagnostics/tests/emptyLhsClassLiterals.kt");
         }
 
+        @Test
+        @TestMetadata("EmptyThrow.kt")
+        public void testEmptyThrow() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/EmptyThrow.kt");
+        }
+
         @Test
         @TestMetadata("EnumEntryAsType.kt")
         public void testEnumEntryAsType() throws Exception {

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java

@@ -321,6 +321,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
             runTest("compiler/testData/diagnostics/tests/emptyLhsClassLiterals.kt");
         }
 
+        @Test
+        @TestMetadata("EmptyThrow.kt")
+        public void testEmptyThrow() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/EmptyThrow.kt");
+        }
+
         @Test
         @TestMetadata("EnumEntryAsType.kt")
         public void testEnumEntryAsType() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeOldFrontendDiagnosticsTestGenerated.java

@@ -321,6 +321,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
             runTest("compiler/testData/diagnostics/tests/emptyLhsClassLiterals.kt");
         }
 
+        @Test
+        @TestMetadata("EmptyThrow.kt")
+        public void testEmptyThrow() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/EmptyThrow.kt");
+        }
+
         @Test
         @TestMetadata("EnumEntryAsType.kt")
         public void testEnumEntryAsType() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiOldFrontendDiagnosticsTestGenerated.java

@@ -321,6 +321,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
             runTest("compiler/testData/diagnostics/tests/emptyLhsClassLiterals.kt");
         }
 
+        @Test
+        @TestMetadata("EmptyThrow.kt")
+        public void testEmptyThrow() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/EmptyThrow.kt");
+        }
+
         @Test
         @TestMetadata("EnumEntryAsType.kt")
         public void testEnumEntryAsType() throws Exception {

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirThrowExpressionTypeChecker.kt

@@ -19,7 +19,7 @@ object FirThrowExpressionTypeChecker : FirThrowExpressionChecker() {
 
         if (!actualType.isSubtypeOf(expectedType, context.session)) {
             reporter.reportOn(
-                expression.exception.source,
+                expression.exception.source ?: expression.source,
                 FirErrors.TYPE_MISMATCH,
                 expectedType,
                 actualType,

compiler/testData/diagnostics/tests/EmptyThrow.kt

@@ -0,0 +1,4 @@
+// FIR_IDENTICAL
+fun someFun(i:Int) {
+    val x = i ?: throw<!SYNTAX!><!>
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -321,6 +321,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
             runTest("compiler/testData/diagnostics/tests/emptyLhsClassLiterals.kt");
         }
 
+        @Test
+        @TestMetadata("EmptyThrow.kt")
+        public void testEmptyThrow() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/EmptyThrow.kt");
+        }
+
         @Test
         @TestMetadata("EnumEntryAsType.kt")
         public void testEnumEntryAsType() throws Exception {