Fix subslicing with bad indices in Encoder::encode_from_utf16.

Due to an oversight, it lacked the fix that `Encoder::encode_from_utf8`
already had.

README.md

@@ -96,6 +96,13 @@ encoding_rs is
 
 ## Release Notes
 
+### 0.6.2
+
+* Fix a panic from subslicing with bad indices in
+  `Encoder::encode_from_utf16`. (Due to an oversight, it lacked the fix that
+  `Encoder::encode_from_utf8` already had.)
+* Micro-optimize error status accumulation in non-streaming case.
+
 ### 0.6.1
 
 * Avoid panic near integer overflow in a case that's unlikely to actually

src/lib.rs

@@ -3718,6 +3718,12 @@ impl Encoder {
                     // ASCII or the Roman state. We are allowed to generate any
                     // printable ASCII excluding \ and ~.
                     total_written += write_ncr(unmappable, &mut dst[total_written..]);
+                    if total_written >= effective_dst_len {
+                        return (CoderResult::OutputFull,
+                                total_read,
+                                total_written,
+                                had_unmappables);
+                    }
                 }
             }
         }