Fix crash on variable-index goto with lazy-declared array label

When goto label[expr] used a variable expression and the label was
lazy-created (no explicit label declaration with range), the compiler
passed a sentinel with empty range (lo=1, hi=0) to
generate_arraylabel_goto which built an empty case node, causing an
access violation during later processing.

Author: fibodevy

compiler/pstatmnt.pas

@@ -2217,8 +2217,16 @@                       ((p.resultdef.typ=recorddef) or
                                         end
                                       else
                                         begin
-                                          { Variable index - generate if-chain for jump }
-                                          code:=generate_arraylabel_goto(tlabelsym(srsym),p);
+                                          { Variable index - generate dispatch for jump.
+                                            Requires explicit label declaration with range. }
+                                          if tlabelsym(srsym).arraylabel_lo<=tlabelsym(srsym).arraylabel_hi then
+                                            code:=generate_arraylabel_goto(tlabelsym(srsym),p)
+                                          else
+                                            begin
+                                              p.free;
+                                              Message(sym_e_label_not_found);
+                                              code:=cerrornode.create;
+                                            end;
                                         end;
                                     end;
                                 end;