proper error for calling nil closure in VM (#24059)

fixes #24057

Instead of crashing the compiler, the VM now gives a stacktrace if a nil
closure is attempted to be called.

compiler/vm.nim

@@ -1378,7 +1378,11 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
       let rb = instr.regB
       let rc = instr.regC
       let bb = regs[rb].node
+      if bb.kind == nkNilLit:
+        stackTrace(c, tos, pc, "attempt to call nil closure")
       let isClosure = bb.kind == nkTupleConstr
+      if isClosure and bb[0].kind == nkNilLit:
+        stackTrace(c, tos, pc, "attempt to call nil closure")
       let prc = if not isClosure: bb.sym else: bb[0].sym
       if prc.offset < -1:
         # it's a callback:

tests/vm/tnilclosurecall.nim

@@ -0,0 +1,8 @@
+discard """
+  errormsg: "attempt to call nil closure"
+  line: 8
+"""
+
+static:
+  let x: proc () = nil
+  x()

tests/vm/tnilclosurecallstacktrace.nim

@@ -0,0 +1,23 @@
+discard """
+  action: reject
+  nimout: '''
+stack trace: (most recent call last)
+tnilclosurecallstacktrace.nim(23, 6) tnilclosurecallstacktrace
+tnilclosurecallstacktrace.nim(20, 6) baz
+tnilclosurecallstacktrace.nim(17, 6) bar
+tnilclosurecallstacktrace.nim(14, 4) foo
+tnilclosurecallstacktrace.nim(14, 4) Error: attempt to call nil closure
+'''
+"""
+
+proc foo(x: proc ()) =
+  x()
+
+proc bar(x: proc ()) =
+  foo(x)
+
+proc baz(x: proc ()) =
+  bar(x)
+
+static:
+  baz(nil)