Preserve VM throw sites in stack traces

lynglib/src/commonTest/kotlin/ScriptTest.kt

@@ -5261,6 +5261,35 @@ class ScriptTest {
         )
     }
 
+    @Test
+    fun testUnexpectedThrowablePreservesThrowSiteStackTrace() = runTest {
+        val caught = evalNamed(
+            "baderrorstack", """
+            fun boom() {
+                val arr = [10, 20, 30]
+                arr[10]
+            }
+            try {
+                boom()
+                "unreachable"
+            } catch (e) {
+                e
+            }
+        """.trimIndent()
+        )
+        val trace = caught.getLyngExceptionMessageWithStackTrace()
+        assertContains(trace, "\n    at baderrorstack:3:1: arr[10]")
+        assertContains(trace, "\n    at baderrorstack:6:1: boom()")
+        assertFalse(trace.contains("catch (e)"))
+    }
+
+    @Test
+    fun testScriptErrorMessageTrimsSourceIndent() = runTest {
+        val x = ScriptError(Pos(Source("trimraw", "    arr[10]"), 0, 4), "boom")
+        assertContains(x.message!!, "\narr[10]\n")
+        assertFalse(x.message!!.contains("\n    arr[10]\n"))
+    }
+
     @Test
     fun testMapIteralAmbiguity() = runTest {
         eval(

lynglib/src/commonTest/kotlin/net/sergeych/lyng/PrintlnOverrideTest.kt

@@ -22,6 +22,8 @@ import net.sergeych.lyng.bridge.globalBinder
 import net.sergeych.lyng.obj.ObjVoid
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
 
 class PrintlnOverrideTest {
 
@@ -84,4 +86,46 @@ class PrintlnOverrideTest {
 
         assertEquals(listOf("gb top level", "gb inside function"), output)
     }
+
+    @Test
+    fun testExceptionPrintStackTraceFormatsPrimaryFrameBlock() = runTest {
+        val scope = Script.newScope()
+        val output = mutableListOf<String>()
+
+        scope.globalBinder().bindGlobalFun("println") {
+            val sb = StringBuilder()
+            for (i in 0 until args.size) {
+                if (i > 0) sb.append(" ")
+                sb.append(string(i))
+            }
+            output.add(sb.toString())
+            ObjVoid
+        }
+
+        scope.eval(
+            """
+            fun boom() {
+                val arr = [10, 20, 30]
+                var a = 10
+                var b = arr[a]
+                b
+            }
+            try {
+                boom()
+            } catch (e) {
+                e.printStackTrace()
+            }
+            """.trimIndent()
+        )
+
+        assertTrue(output.isNotEmpty())
+        assertEquals(
+            "IndexOutOfBoundsException: Index 10 out of bounds for length 3 at eval:4:9:",
+            output[0]
+        )
+        assertEquals("var b = arr[a]", output[1])
+        assertEquals("--------^", output[2])
+        assertTrue(output.size >= 4)
+        assertFalse(output.any { it == "        at eval:4:9: var b = arr[a]" })
+    }
 }