Resolve nits and fix failures (hopefully)

Author: ryzokuken

lib/fs.js

@@ -2008,13 +2008,13 @@ function ReadStream(path, options) {
   this.closed = false;
 
   if (this.start !== undefined) {
-    if (typeof this.start !== 'number' || Number.isNaN(this.start)) {
-      throw new ERR_INVALID_ARG_TYPE('start', 'number', this.start);
+    if (typeof this.start !== 'number' || !Number.isInteger(this.start)) {
+      throw new ERR_INVALID_ARG_TYPE('start', 'integer', this.start);
     }
     if (this.end === undefined) {
       this.end = Infinity;
-    } else if (typeof this.end !== 'number' || Number.isNaN(this.end)) {
-      throw new ERR_INVALID_ARG_TYPE('end', 'number', this.end);
+    } else if (typeof this.end !== 'number' || !Number.isInteger(this.end)) {
+      throw new ERR_INVALID_ARG_TYPE('end', 'integer', this.end);
     }
 
     if (this.start > this.end) {
@@ -2028,8 +2028,10 @@ function ReadStream(path, options) {
   // Backwards compatibility: Make sure `end` is a number regardless of `start`.
   // TODO(addaleax): Make the above typecheck not depend on `start` instead.
   // (That is a semver-major change).
-  if (typeof this.end !== 'number' || Number.isNaN(this.end))
+  if (typeof this.end !== 'number')
     this.end = Infinity;
+  else if (!Number.isInteger(this.end))
+    throw new ERR_INVALID_ARG_TYPE('end', 'integer', this.end);
 
   if (typeof this.fd !== 'number')
     this.open();

test/parallel/test-fs-read-stream-throw-type-error.js

@@ -22,8 +22,7 @@ const createReadStreamErr = (path, opt) => {
     {
       code: 'ERR_INVALID_ARG_TYPE',
       type: TypeError
-    }
-  );
+    });
 };
 
 createReadStreamErr(example, 123);