Fix return type problem

rebar.config.script

@@ -24,6 +24,9 @@ CFlags =
 
 [
     {require_min_otp_vsn, "21"},
+
+    {xref_checks, [undefined_function_calls]},
+
     {port_env, [
         %% Default darwin ldflags causes loading of system sqlite. Removed -bundle flag.
         {"darwin", "DRV_LDFLAGS",
@@ -46,5 +49,14 @@ CFlags =
     {provider_hooks,
         [{post,
         [{compile, {pc, compile}},
-            {clean, {pc, clean}}]}]}
+            {clean, {pc, clean}}]}]},
+
+    {dialyzer, [
+        {warnings, [
+            unmatched_returns,
+            error_handling,
+            race_conditions
+            % underspecs
+        ]}
+    ]}
 ].

src/esqlite3.erl

@@ -361,8 +361,12 @@ exec(Sql, [], #connection{raw_connection=RawConnection}, Timeout) ->
     receive_answer(RawConnection, Ref, Timeout);
 exec(Sql, Params, Connection, Timeout) ->
     {ok, Statement} = prepare(Sql, Connection, Timeout),
-    bind(Statement, Params),
-    step(Statement, Timeout).
+    case bind(Statement, Params) of
+        ok ->
+            step(Statement, Timeout);
+        {error, _}=Error ->
+            Error
+    end.
 
 
 %% @doc Return the number of affected rows of last statement.