Don't panic when replacement glyph is not found #11246

Job	Run time
Format + check + test	16m 3s
android	1m 17s
cargo-deny aarch64-apple-darwin	44s
Check wasm32 + wasm-bindgen	2m 28s
Check Windows	6m 13s
cargo-deny aarch64-linux-android	41s
cargo-deny i686-pc-windows-gnu	44s
cargo-deny i686-pc-windows-msvc	40s
cargo-deny i686-unknown-linux-gnu	42s
cargo-deny wasm32-unknown-unknown	39s
cargo-deny x86_64-apple-darwin	44s
cargo-deny x86_64-pc-windows-gnu	49s
cargo-deny x86_64-pc-windows-msvc	42s
cargo-deny x86_64-unknown-linux-gnu	39s
cargo-deny x86_64-unknown-linux-musl	38s
cargo-deny x86_64-unknown-redox	38s
	34m 21s

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