fix: guard against proxy traps raising exceptions in REPL tokenizer

PR-URL: stdlib-js#4457
Reviewed-by: Athan Reines <[email protected]>

Author: Snehil-Shah

lib/node_modules/@stdlib/repl/lib/tokenizer.js

@@ -24,6 +24,7 @@
 
 var parse = require( 'acorn-loose' ).parse;
 var walk = require( 'acorn-walk' );
+var hasProp = require( '@stdlib/assert/has-property' );
 var linkedList = require( '@stdlib/utils/linked-list' );
 var contains = require( '@stdlib/array/base/assert/contains' );
 var resolveLocalScopes = require( './resolve_local_scopes.js' );
@@ -227,7 +228,7 @@ function tokenizer( line, context ) {
 		for ( i = 0; i < COMMANDS.length; i++ ) {
 			command = COMMANDS[ i ];
 			if ( node.name === command[ 0 ] ) {
-				tokens.push( {
+				tokens.push({
 					'value': node.name,
 					'type': 'command',
 					'start': node.start,
@@ -240,14 +241,14 @@ function tokenizer( line, context ) {
 		identifier = context[ node.name ];
 		if ( identifier ) {
 			if ( isLiteralType( typeof identifier ) ) {
-				tokens.push( {
+				tokens.push({
 					'value': node.name,
 					'type': 'variable',
 					'start': node.start,
 					'end': node.end
 				});
 			} else {
-				tokens.push( {
+				tokens.push({
 					'value': node.name,
 					'type': typeof identifier,
 					'start': node.start,
@@ -313,19 +314,27 @@ function tokenizer( line, context ) {
 			}
 			// Case: 'bar' in `foo['bar']` - property already pushed as a string token. Ignore...
 			if ( property.value.type === 'Literal' ) {
-				obj = obj[ property.value.value ];
-				if ( !obj ) {
-					// Property not found in context:
+				try {
+					if ( !hasProp( obj, property.value.value ) ) {
+						// Property not found in context:
+						break;
+					}
+					obj = obj[ property.value.value ];
+				} catch ( error ) { // eslint-disable-line no-unused-vars
 					break;
 				}
 				property = properties.next();
 				continue;
 			}
 			// Case: `foo.bar` - resolve property and push it as a token...
 			if ( property.value.type === 'Identifier' ) {
-				obj = obj[ property.value.name ];
-				if ( !obj ) {
-					// Property not found in context:
+				try {
+					if ( !hasProp( obj, property.value.name ) ) {
+						// Property not found in context:
+						break;
+					}
+					obj = obj[ property.value.name ];
+				} catch ( error ) { // eslint-disable-line no-unused-vars
 					break;
 				}
 				if ( !compute ) {
@@ -356,9 +365,13 @@ function tokenizer( line, context ) {
 					// Couldn't compute the internal `MemberExpression` into a definite name:
 					break;
 				}
-				obj = obj[ computed ];
-				if ( !obj ) {
-					// Property not found in context:
+				try {
+					if ( !hasProp( obj, computed ) ) {
+						// Property not found in context:
+						break;
+					}
+					obj = obj[ computed ];
+				} catch ( error ) { // eslint-disable-line no-unused-vars
 					break;
 				}
 				property = properties.next();