Fix a crash in HyTypeError.__str__

NEWS

@@ -39,6 +39,8 @@ Changes from 0.13.0
    * Fixed a crash when `with` suppresses an exception. `with` now returns
      `None` in this case.
    * Fixed a crash when --repl-output-fn raises an exception
+   * Fixed a crash when HyTypeError was raised with objects that had no
+     source position
    * `assoc` now evaluates its arguments only once each
    * `break` and `continue` now raise an error when given arguments
      instead of silently ignoring them

hy/errors.py

@@ -43,6 +43,11 @@ class HyTypeError(TypeError):
 
     def __str__(self):
 
+        result = ""
+
+        if all(getattr(self.expression, x, None) is not None
+               for x in ("start_line", "start_column", "end_column")):
+
             line = self.expression.start_line
             start = self.expression.start_column
             end = self.expression.end_column
@@ -56,8 +61,6 @@ class HyTypeError(TypeError):
                 else:
                     length = len(source[0]) - start
 
-        result = ""
-
             result += '  File "%s", line %d, column %d\n\n' % (self.filename,
                                                                line,
                                                                start)
@@ -79,6 +82,9 @@ class HyTypeError(TypeError):
                 result += '  %s\n' % colored.red("".join(source[-1]))
                 result += '  %s\n' % colored.green('-'*(end-1) + '^')
 
+        else:
+            result += '  File "%s", unknown location\n' % self.filename
+
         result += colored.yellow("%s: %s\n\n" %
                                  (self.__class__.__name__,
                                   self.message.encode('utf-8')))

tests/test_bin.py

@@ -138,6 +138,16 @@ def test_bin_hy_stdin_except_do():
     assert "zzz" in output
 
 
+def test_bin_hy_stdin_unlocatable_hytypeerror():
+    # https://github.com/hylang/hy/issues/1412
+    # The chief test of interest here is the returncode assertion
+    # inside run_cmd.
+    _, err = run_cmd("hy", """
+        (import hy.errors)
+        (raise (hy.errors.HyTypeError '[] (+ "A" "Z")))""")
+    assert "AZ" in err
+
+
 def test_bin_hy_stdin_bad_repr():
     # https://github.com/hylang/hy/issues/1389
     output, err = run_cmd("hy", """