Merge pull request #275 from tsloughter/pkg_vsn_error

handle bad package version with error message

src/rebar_prv_install_deps.erl

@@ -97,6 +97,8 @@ do(State) ->
     end.
 
 -spec format_error(any()) -> iolist().
+format_error({bad_constraint, Name, Constraint}) ->
+    io_lib:format("Unable to parse version for package ~s: ~s", [Name, Constraint]);
 format_error({parse_dep, Dep}) ->
     io_lib:format("Failed parsing dep ~p", [Dep]);
 format_error({missing_package, Package, Version}) ->
@@ -510,7 +512,7 @@ parse_goal(Name, Constraint) ->
         {match, [Op, Vsn]} ->
             {Name, Vsn, binary_to_atom(Op, utf8)};
         nomatch ->
-            fail
+            throw(?PRV_ERROR({bad_constraint, Name, Constraint}))
     end.
 
 warn_skip_deps(AppInfo, State) ->

src/rebar_prv_update.erl

@@ -49,7 +49,7 @@ do(State) ->
         ok
     catch
         _E:_C ->
-            ?PRV_ERROR(package_index_write)
+            throw(?PRV_ERROR(package_index_write))
     end,
 
     {ok, State}.