[FIR-TEST] Throw RuntimeException instead of AssertionError in FirResolveBench

This is needed for better usability of testing of changes which
  brake testdata and introduce new exceptions from compiler at same time

compiler/tests-common/tests/org/jetbrains/kotlin/fir/AbstractFirOldFrontendDiagnosticsTest.kt

@@ -26,12 +26,12 @@ abstract class AbstractFirOldFrontendDiagnosticsTest : AbstractFirDiagnosticsTes
 
     override fun runAnalysis(testDataFile: File, testFiles: List<TestFile>, firFilesPerSession: Map<FirSession, List<FirFile>>) {
         if (testFiles.any { "FIR_IGNORE" in it.directives }) return
-        val failure: AssertionError? = try {
+        val failure: FirRuntimeException? = try {
             for ((_, firFiles) in firFilesPerSession) {
                 doFirResolveTestBench(firFiles, FirTotalResolveTransformer().transformers, gc = false)
             }
             null
-        } catch (e: AssertionError) {
+        } catch (e: FirRuntimeException) {
             e
         }
         val failureFile = File(testDataFile.path.replace(".kt", ".fail"))
@@ -57,13 +57,11 @@ abstract class AbstractFirOldFrontendDiagnosticsTest : AbstractFirDiagnosticsTes
         }
     }
 
-    private fun checkFailureFile(failure: AssertionError, failureFile: File) {
+    private fun checkFailureFile(failure: FirRuntimeException, failureFile: File) {
         val failureMessage = buildString {
             appendln(failure.message)
-            failure.cause?.let {
+            append("Cause: ")
-                append("Cause: ")
+            appendln(failure.cause)
-                appendln(it)
-            }
         }
         KotlinTestUtils.assertEqualsToFile(failureFile, failureMessage)
     }

compiler/tests-common/tests/org/jetbrains/kotlin/fir/FirResolveBench.kt

@@ -297,7 +297,7 @@ class FirResolveBench(val withProgress: Boolean) {
     fun throwFailure() {
         if (fails.any()) {
             val (transformerClass, failure, file) = fails.first()
-            throw AssertionError("Failures detected in ${transformerClass.simpleName}, file: $file", failure)
+            throw FirRuntimeException("Failures detected in ${transformerClass.simpleName}, file: $file", failure)
         }
     }
 
@@ -417,3 +417,5 @@ private fun RTableContext.printMeasureAsTable(measure: FirResolveBench.Measure,
         cell(measure.gcCollections.toString())
     }
 }
+
+class FirRuntimeException(override val message: String, override val cause: Throwable) : RuntimeException(message, cause)