[Bug 1911188] [NEW] qemu-system-x86_64 prints obscure error message and exits when encountering an empty argument

[Violet]

Public bug reported:

QEMU emulator version 4.2.1 (qemu-4.2.1-1.fc32) on Fedora 32.

When writing a script to start qemu automatically, I ran into a very
confusing error message due to a bug in my script and had trouble
understanding it. I isolated the problem to the following:

$ qemu-system-x86_64 ""
qemu-system-x86_64: Initialization of device ide-hd failed: Device needs media, 
but drive is empty

As you can see, running qemu with an empty argument prints a seemingly
random and unrelated error message about an ide-hd device, and the
program immediately exits with code 1. This happens when an empty
argument appears anywhere in the arguments list, always causing the
program to immediately die with this error.

This is a simply baffling message to be encountering when the problem is
really an empty argument.

Expected behaviour: Either flatly ignore the empty argument, or at most
trigger a warning (eg, "warning: saw empty argument"). It should not at
all prevent the program from running.

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1911188

Title:
  qemu-system-x86_64 prints obscure error message and exits when
  encountering an empty argument

Status in QEMU:
  New

Bug description:
  QEMU emulator version 4.2.1 (qemu-4.2.1-1.fc32) on Fedora 32.

  When writing a script to start qemu automatically, I ran into a very
  confusing error message due to a bug in my script and had trouble
  understanding it. I isolated the problem to the following:

  $ qemu-system-x86_64 ""
  qemu-system-x86_64: Initialization of device ide-hd failed: Device needs 
media, but drive is empty

  As you can see, running qemu with an empty argument prints a seemingly
  random and unrelated error message about an ide-hd device, and the
  program immediately exits with code 1. This happens when an empty
  argument appears anywhere in the arguments list, always causing the
  program to immediately die with this error.

  This is a simply baffling message to be encountering when the problem
  is really an empty argument.

  Expected behaviour: Either flatly ignore the empty argument, or at
  most trigger a warning (eg, "warning: saw empty argument"). It should
  not at all prevent the program from running.

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