Fix multiple error bug

This commit fixes a bug where the done callback may be called more
than once.

Author: kgryte

lib/node_modules/@stdlib/utils/inmap-async/lib/limit.js

@@ -21,8 +21,8 @@ var debug = require( 'debug' )( 'inmap-async:limit' );
 */
 function limit( collection, opts, fcn, done ) {
 	var maxIndex;
-	var errFLG;
 	var count;
+	var flg;
 	var lim;
 	var len;
 	var idx;
@@ -78,14 +78,14 @@ function limit( collection, opts, fcn, done ) {
 		* @returns {void}
 		*/
 		function cb( error, result ) {
-			if ( error ) {
-				errFLG = true;
-				return clbk( error );
-			}
-			if ( errFLG ) {
+			if ( flg ) {
 				// Prevent further processing of collection elements:
 				return;
 			}
+			if ( error ) {
+				flg = true;
+				return clbk( error );
+			}
 			collection[ j ] = result;
 			clbk();
 		} // end FUNCTION cb()

lib/node_modules/@stdlib/utils/inmap-async/test/test.factory.js

@@ -814,6 +814,37 @@ tape( 'if an error is encountered while processing a collection element, the ret
 	}
 });
 
+tape( 'if an error is encountered while processing a collection element, the returned function suspends execution and immediately returns the error (concurrent)', function test( t ) {
+	var inmapAsync;
+	var count;
+	var arr;
+
+	inmapAsync = factory( fcn );
+
+	arr = [ 500, 500, 500 ];
+	count = 0;
+	inmapAsync( arr, done );
+
+	function fcn( value, index, next ) {
+		count += 1;
+		setTimeout( onTimeout, value );
+
+		function onTimeout() {
+			return next( new Error( 'beep' ) );
+		}
+	}
+
+	function done( error ) {
+		t.strictEqual( count, 3, 'suspends execution' );
+		if ( error ) {
+			t.pass( error.message );
+		} else {
+			t.fail( 'did not return an error' );
+		}
+		t.end();
+	}
+});
+
 tape( 'if an error is encountered while processing a collection element, a collection may be partially mutated', function test( t ) {
 	var inmapAsync;
 	var expected;

lib/node_modules/@stdlib/utils/inmap-async/test/test.inmap.js

@@ -722,6 +722,34 @@ tape( 'if an error is encountered while processing a collection element, the fun
 	}
 });
 
+tape( 'if an error is encountered while processing a collection element, the function suspends execution and immediately returns the error (concurrent)', function test( t ) {
+	var count;
+	var arr;
+
+	arr = [ 500, 500, 500 ];
+	count = 0;
+	inmapAsync( arr, fcn, done );
+
+	function fcn( value, index, next ) {
+		count += 1;
+		setTimeout( onTimeout, value );
+
+		function onTimeout() {
+			return next( new Error( 'beep' ) );
+		}
+	}
+
+	function done( error ) {
+		t.strictEqual( count, 3, 'suspends execution' );
+		if ( error ) {
+			t.pass( error.message );
+		} else {
+			t.fail( 'did not return an error' );
+		}
+		t.end();
+	}
+});
+
 tape( 'if an error is encountered while processing a collection element, a collection may be partially mutated', function test( t ) {
 	var expected;
 	var arr;