[Bug]: resource.MustParse panics on invalid user input in vm.go

[mrhillsman]

Bug Description

internal/vm/vm.go uses resource.MustParse() in two places (lines 125 and 170) to parse user-supplied memory and disk-size strings. MustParse panics instead of returning an error when the input is malformed. A CLI tool should never panic on bad user input — it should return a clear error message.

Steps to Reproduce

1. Run virtwork run --workloads cpu --memory "not-a-quantity"
2. Observe a panic/stack trace instead of a user-friendly error

Expected Behavior

virtwork prints a clear error message like invalid memory value "not-a-quantity": ... and exits with a non-zero status code.

Actual Behavior

The process panics with an unrecoverable stack trace from resource.MustParse.

Affected Code

• internal/vm/vm.go:125 — resource.MustParse(opts.Memory)
• internal/vm/vm.go:170 — resource.MustParse(size) for data disk

Command

• virtwork run

Workload Type

• Not applicable (affects all workloads)

Proposed Fix

Replace resource.MustParse() with resource.ParseQuantity() which returns (Quantity, error). Propagate the error up through BuildVM / buildDataVolume to the caller.