Correctly bubble up errors from libbacktrace

src/libstd/sys_common/gnu/libbacktrace.rs

@@ -30,6 +30,12 @@ where F: FnMut(&[u8], libc::c_int) -> io::Result<()>
     let ret;
     let fileline_count = {
         let state = unsafe { init_state() };
+        if state.is_null() {
+            return Err(io::Error::new(
+                io::ErrorKind::Other,
+                "failed to allocate libbacktrace state")
+            )
+        }
         let mut fileline_win: &mut [FileLine] = &mut fileline_buf;
         let fileline_addr = &mut fileline_win as *mut &mut [FileLine];
         ret = unsafe {
@@ -62,8 +68,11 @@ pub fn resolve_symname<F>(frame: Frame,
     let symname = {
         let state = unsafe { init_state() };
         if state.is_null() {
-            None
-        } else {
+            return Err(io::Error::new(
+                io::ErrorKind::Other,
+                "failed to allocate libbacktrace state")
+            )
+        }
         let mut data = ptr::null();
         let data_addr = &mut data as *mut *const libc::c_char;
         let ret = unsafe {
@@ -80,7 +89,6 @@ pub fn resolve_symname<F>(frame: Frame,
                 CStr::from_ptr(data).to_str().ok()
             }
         }
-        }
     };
     callback(symname)
 }