Ensure error return code when worker is emitting an error message

Author: HugoGGuerrier

lkql_checker/src/gnatcheck-compiler.adb

@@ -520,6 +520,7 @@ package body Gnatcheck.Compiler is
             and then Line (1 .. 14) = "WORKER_ERROR: "
          then
             Error (Line (15 .. Line_Len));
+            Detected_Internal_Error := @ + 1;
             Errors := True;
          else
             Analyze_Line (Line (1 .. Line_Len));

testsuite/tests/gnatcheck_errors/lkql_rule_error/main.adb

@@ -0,0 +1,4 @@
+procedure Main is
+begin
+   null;
+end Main;

testsuite/tests/gnatcheck_errors/lkql_rule_error/rules/test.lkql

@@ -0,0 +1,3 @@
+@check(message="blah")
+fun test(node) =
+    blah

testsuite/tests/gnatcheck_errors/lkql_rule_error/test.out

@@ -0,0 +1,37 @@
+gnatcheck: test.lkql:3:05: Unknown symbol: blah
+gnatcheck: Errors during analysis
+1. Summary
+
+   fully compliant sources               : 1
+   sources with exempted violations only : 0
+   sources with non-exempted violations  : 0
+   unverified sources                    : 0
+   total sources                         : 1
+   ignored sources                       : 0
+
+   non-exempted violations               : 0
+   rule exemption warnings               : 0
+   compilation errors                    : 0
+   exempted violations                   : 0
+   internal errors                       : 2
+
+2. Exempted Coding Standard Violations
+
+   no exempted violations detected
+
+3. Non-exempted Coding Standard Violations
+
+   no non-exempted violations detected
+
+4. Rule exemption problems
+
+   no rule exemption problems detected
+
+5. Language violations
+
+   no language violations detected
+
+6. Gnatcheck internal errors
+
+
+>>>program returned status code 2

testsuite/tests/gnatcheck_errors/lkql_rule_error/test.yaml

@@ -0,0 +1,7 @@
+driver: gnatcheck
+rules_dirs:
+  - rules
+input_sources:
+  - main.adb
+rules:
+  - +RTest