derive: fail if requested template block is missing #1057

Job	Run time
DevSkim	27s
Audit	18s
Check order in Cargo.toml	5s
Book	3s
Docs (rinja)	22s
Jinja2-Assumptions	8s
Rustfmt	15s
Docs (rinja_derive)	22s
Typos	26s
Docs (rinja_parser)	13s
MSRV	22s
Package (examples/actix-web-app)	1m 0s
Test (ubuntu-latest, stable)	41s
Package (examples/axum-app)	46s
Test (ubuntu-latest, beta)	42s
Package (examples/poem-app)	44s
Test (macos-latest, stable)	52s
Package (examples/rocket-app)	1m 11s
Test (windows-latest, stable)	2m 25s
Package (examples/salvo-app)	1m 12s
Package (examples/warp-app)	1m 1s
Package (fuzzing)	32s
Package (rinja)	38s
Package (rinja_derive)	16s
Package (rinja_derive_standalone)	52s
Package (rinja_parser)	36s
Package (testing)	1m 0s
Package (testing-alloc)	23s
Package (testing-no-std)	19s
Package (testing-renamed)	30s
Cluster-Fuzz	13m 59s
Fuzz (all)	5m 13s
Fuzz (filters)	5m 18s
Fuzz (html)	5m 15s
Fuzz (parser)	5m 17s
	53m 43s

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