grype v0.64.0 template zeroes the template content

[abg]

What happened:

Running grype v0.64.0 with grype -o template -t my.tmpl zeros out my template file.

What you expected to happen:

Expected template to be read and templated output emitted similar to earlier to releases.

How to reproduce it (as minimally and precisely as possible):

# curl -Ls 'https://github.com/anchore/grype/raw/main/templates/table.tmpl' > table.tmpl
# ls -lah table.tmpl
-rw-r--r-- 1 root root 2.9K Jul 14 03:29 table.tmpl
# grype --quiet -o template -t table.tmpl dir:.
# ls -lah table.tmpl
-rw-r--r-- 1 root root 0 Jul 14 03:27 table.tmpl

Anything else we need to know?:

grype v0.63.1 seems to work with templates. This change seems related to #1346

Environment:

• Output of grype version:

# grype version
Application:          grype
Version:              0.64.0
Syft Version:         v0.85.0
BuildDate:            2023-07-13T15:19:47Z
GitCommit:            37f436cfb6eb871bfde9cfcb1a360c510751afc9
GitDescription:       v0.64.0
Platform:             linux/amd64
GoVersion:            go1.19.10
Compiler:             gc
Supported DB Schema:  5

• OS (e.g: cat /etc/os-release or similar):

# cat /etc/os-release
PRETTY_NAME="Ubuntu 22.04.2 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.2 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy

[willmurphyscode]

Thanks for the bug report @abg! I've reproduced the issue locally and am working on a fix.