feat: add runtime error support with source paths, line info, and stack traces

Introduce primitive error signaling, runtime error handling with callstack printing, and fiber termination on error. Add source file path and method name tracking to functions, along with debug line number information. Update arithmetic operators to error on non-numeric operands and implement proper "method not found" runtime errors. Refactor the test runner to expect runtime errors with exit code 70 (EX_SOFTWARE) and update the C API to accept source paths in wrenInterpret and wrenCompile. Rename WrenNativeMethodFn to WrenForeignMethodFn and adjust related typedefs. Add debug source line arrays to compilers and functions, and replace the old debug dump functions with new print-based variants that display line numbers.

runtests

@@ -35,7 +35,9 @@ else:
 EXPECT_PATTERN = re.compile(r'// expect: (.*)')
 EXPECT_ERROR_PATTERN = re.compile(r'// expect error')
 EXPECT_ERROR_LINE_PATTERN = re.compile(r'// expect error line (\d+)')
-ERROR_PATTERN = re.compile(r'\[Line (\d+)\] Error')
+EXPECT_RUNTIME_ERROR_PATTERN = re.compile(r'// expect runtime error: (.+)')
+ERROR_PATTERN = re.compile(r'\[.* line (\d+)\] Error')
+STACK_TRACE_PATTERN = re.compile(r'\[.* line (\d+)\] in \(script\)')
 SKIP_PATTERN = re.compile(r'// skip: (.*)')
 NONTEST_PATTERN = re.compile(r'// nontest')
 
@@ -102,6 +104,8 @@ def run_test(path):
   # Read the test and parse out the expectations.
   expect_output = []
   expect_error = []
+  expect_runtime_error_line = 0
+  expect_runtime_error = None
   expect_return = 0
 
   print_line('Passed: ' + color.GREEN + str(passed) + color.DEFAULT +
@@ -118,16 +122,21 @@ def run_test(path):
       match = EXPECT_ERROR_PATTERN.search(line)
       if match:
         expect_error.append(line_num)
-        # If we expect compile errors in the test, it should return
-        # exit code 1.
-        expect_return = 1
+        # If we expect compile errors, it should exit with EX_DATAERR.
+        expect_return = 65
 
       match = EXPECT_ERROR_LINE_PATTERN.search(line)
       if match:
         expect_error.append(int(match.group(1)))
-        # If we expect compile errors in the test, it should return
-        # exit code 1.
-        expect_return = 1
+        # If we expect compile errors, it should exit with EX_DATAERR.
+        expect_return = 65
+
+      match = EXPECT_RUNTIME_ERROR_PATTERN.search(line)
+      if match:
+        expect_runtime_error_line = line_num
+        expect_runtime_error = match.group(1)
+        # If we expect a runtime error, it should exit with EX_SOFTWARE.
+        expect_return = 70
 
       match = SKIP_PATTERN.search(line)
       if match:
@@ -150,21 +159,44 @@ def run_test(path):
   fails = []
 
   # Validate that no unexpected errors occurred.
-  if expect_return == 1 and err != '':
+  if expect_return != 0 and err != '':
     lines = err.split('\n')
-    while len(lines) > 0:
-      line = lines.pop(0)
-      match = ERROR_PATTERN.search(line)
-      if match:
-        if float(match.group(1)) not in expect_error:
-          fails.append('Unexpected error:')
+    if expect_runtime_error:
+      # Make sure we got the right error.
+      if lines[0] != expect_runtime_error:
+        fails.append('Expected runtime error "' + expect_runtime_error +
+          '" and got:')
+        fails.append(lines[0])
+
+      # Make sure the stack trace has the right line.
+      match = STACK_TRACE_PATTERN.search(lines[1])
+      if not match:
+        fails.append('Expected stack trace and got:')
+        fails.append(lines[1])
+      else:
+        stack_line = int(match.group(1))
+        if stack_line != expect_runtime_error_line:
+          fails.append('Expected runtime error on line ' +
+              str(expect_runtime_error_line) + ' but was on line ' +
+              str(stack_line))
+    else:
+      lines = err.split('\n')
+      while len(lines) > 0:
+        line = lines.pop(0)
+        match = ERROR_PATTERN.search(line)
+        if match:
+          if float(match.group(1)) not in expect_error:
+            fails.append('Unexpected error:')
+            fails.append(line)
+        elif line != '':
+          fails.append('Unexpected output on stderr:')
           fails.append(line)
-      elif line != '':
-        fails.append('Unexpected output on stderr:')
-        fails.append(line)
   else:
     for line in expect_error:
       fails.append('Expected error on line ' + str(line) + ' and got none.')
+    if expect_runtime_error:
+      fails.append('Expected runtime error ' + expect_runtime_error +
+          ' and got none.')
 
   # Validate the exit code.
   if proc.returncode != expect_return: