Write a "Hello" interpreter Background
Hello is a language &quot;written&quot; by Anne Veling, which errors if the program does not contain only h, and will print Hello World for every h
Task
You are to write an interpreter/compiler for Hello.
Example in Python
import os
i = input(&quot;Program: &quot;)
for a in i:
    if a != 'h':
        print(&quot;err&quot;)
        quit()
    else:
        print(&quot;Hello World&quot;)

Details

If the program is not only hs, it must print err or error (case-insensitive)
It's okay if you print &quot;Hello World&quot;s before your program discovers a non-h character and errors, however, the program must halt if a non-h
You may throw an error, as long as you print err/error before throwing, or by using a custom error builtin, like raise SyntaxError('err') in python. (basically, you have to purposefully error with err/error
Assume the program will not be empty
Output can have a trailing newline, space, or nothing to separate Hello Worlds
If a program has multiple lines, it should error (due to \n not being an h)
You can assume that input will always be ASCII 33-126 and 10 (decimal)
The hs are case sensitive (so H is not a valid program)
instruction is found
This is code-golf, shortest answer wins

Test cases
Input:

h

Output:

Hello World

Input:

hhhhhh

Output:

Hello WorldHello WorldHello WorldHello WorldHello WorldHello World

(again, it doesn't matter whether it's spaces, newlines, or nothing to separate `Hello World`s

Input:

rubbish

Output:

err

Input:

huh

Output:

Hello Worlderr

Or

err

First challenge so please have mercy
Lenguage, \$1.42 \times 10^{122}\$ bytes
minus a lot of bytes thanks to Kevin Cruijssen and Bubbler
hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh...

This is 142099843608359281286315447494338058415442968773543757980908246691462388164856076679905341690709953072132211450166077106439 hs, which also makes it a valid Hello program, though not one you'd want to run. The original brainfuck code is 140 135 bytes:
,[&gt;-[&lt;--&gt;-----]+&lt;--[&gt;]&gt;[[--&gt;-[&gt;&gt;+&gt;-----&lt;&lt;]&lt;--&lt;---]&gt;-.&gt;&gt;&gt;+.&gt;&gt;..+++.&gt;&gt;.&gt;.&lt;&lt;&lt;.+++.------.&lt;&lt;-.[&gt;]&gt;&gt;&gt;&gt;,&gt;]&lt;]&lt;[[&gt;++&lt;+++++]&gt;-.+++++++++++++..&gt;]

Try it online!
This prints Hello World every time it sees a h through a modification of the shortest known Hello, World! program, stopping the loop and printing err if it sees anything other than a h.