csharp, 162 bytes

Result

AC

Duration

1390ms

Code [DL]

using S=System.Console;class A{static int r=>int.Parse(S.ReadLine());static void Main(){for(int h=r,w=r,y=h;;)S.Write($"*{"*\n".PadLeft(w,y%h>y/y--?' ':'*')}");}}

stdin

77
83

stdout

***********************************************************************************
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***********************************************************************************

stderr

Unhandled Exception:
System.DivideByZeroException: Attempted to divide by zero.
  at A.Main () [0x00013] in <4a4f0e901f7f4d028904154a773e6742>:0 
[ERROR] FATAL UNHANDLED EXCEPTION: System.DivideByZeroException: Attempted to divide by zero.
  at A.Main () [0x00013] in <4a4f0e901f7f4d028904154a773e6742>:0