Bug : Crash on report summary vs ok on report html (when file does not exists)

[LasneF]

test done on :
openapi-changes version: 0.0.69 | compiled: Tue, 22 Oct 2024 14:03:15 UTC

Given the command

openapi-changes summrary a.yml b.yml where b fors not exists it crashes with the following stack

starting work. (0s)panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x60 pc=0xa13257]

goroutine 18 [running]:
github.com/pterm/pterm.(*SpinnerPrinter).Fail(0xc00002e620?, {0xc000036750?, 0xc00008ff30?, 0x1?})
        /home/runner/go/pkg/mod/github.com/pterm/pterm@v0.12.79/spinner_printer.go:234 +0x17
github.com/pb33f/openapi-changes/cmd.GetSummaryCommand.func1.1(0xc0001f0000, 0xc0001f0070)
        /home/runner/work/openapi-changes/openapi-changes/cmd/summary.go:146 +0x775
created by github.com/pb33f/openapi-changes/cmd.GetSummaryCommand.func1 in goroutine 

IMPORTTANT

openapi-changes html-report a.yml b.yml where b fors not exists
it fails correctly with an message

ERROR Stopped: cannot read modified spec: open perforce.yml: The system cannot find the file specified.
DONE completed processing

ERROR open perforce.yml: The system cannot find the file specified.
Error: unable to process specifications