Fix undefined variables/methods.

mesonbuild/environment.py

@@ -738,7 +738,7 @@ class Environment:
             if p.returncode == 1 and err.startswith('usage'): # OSX
                 return ArLinker(linker)
         self._handle_exceptions(popen_exceptions, linkers, 'linker')
-        raise EnvironmentException('Unknown static linker "%s"' % ' '.join(linker))
+        raise EnvironmentException('Unknown static linker "%s"' % ' '.join(linkers))
 
     def detect_ccache(self):
         try:

mesonbuild/interpreter.py

@@ -100,7 +100,7 @@ class RunProcess(InterpreterObject):
         try:
             return Popen_safe(command_array, env=child_env, cwd=cwd)
         except FileNotFoundError:
-            raise InterpreterException('Could not execute command "%s".' % cmd_name)
+            raise InterpreterException('Could not execute command "%s".' % ' '.join(command_array))
 
     def returncode_method(self, args, kwargs):
         return self.returncode