Fix some errors found when run typescript compiler

[Mingun]

Some errors, catched with the following change in the tsconfig.json and running npm run ts:

 tsconfig.json | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tsconfig.json b/tsconfig.json
index fe8a4420..bee30bbf 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -4,7 +4,7 @@
     "module": "commonjs",                           /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
     // "lib": [],                                   /* Specify library files to be included in the compilation. */
     "allowJs": true,                                /* Allow javascript files to be compiled. */
-    "checkJs": false,                               /* Report errors in .js files. */
+    "checkJs": true,                                /* Report errors in .js files. */
     // "jsx": "preserve",                           /* Specify JSX code generation: 'preserve', 'react-native', 'react', 'react-jsx' or 'react-jsxdev'. */
     "declaration": true,                            /* Generates corresponding '.d.ts' file. */
     "declarationMap": false,                         /* Generates a sourcemap for each corresponding '.d.ts' file. */
@@ -14,8 +14,8 @@
     "removeComments": true,                         /* Do not emit comments to output. */
 
   /* over time we will enable these */
-    // "strict": true,                              /* Enable all strict type-checking options. */
-    // "noImplicitAny": true,                       /* Raise error on expressions and declarations with an implied 'any' type. */
+    "strict": true,                                 /* Enable all strict type-checking options. */
+    "noImplicitAny": false,                         /* Raise error on expressions and declarations with an implied 'any' type. */
     // "strictNullChecks": true,                    /* Enable strict null checks. */
     // "strictFunctionTypes": true,                 /* Enable strict checking of function types. */
     // "strictBindCallApply": true,                 /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
@@ -34,5 +34,5 @@
     "skipLibCheck": true,                           /* Skip type checking of declaration files. */
     "forceConsistentCasingInFileNames": true        /* Disallow inconsistently-cased references to the same file. */
   },
-  "include": ["./lib/**/*.js", "./test/**/*.spec.js", "./benchmark/*.js"]
+  "include": ["./lib/**/*.js", "./test/**/*.spec.js"]
 }

Because I anyway replace all arguments usage with the rest parameters, I also made a small improvement in the default visitor behavior for visitExpression methods: make it returns a value of the visited expression. Now you no longer need to override that methods just to return values

[Mingun]

Rebased and ready to merge