char index no overflow, but needs to be higher

Cargo.toml

@@ -7,4 +7,14 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-fontdue = "0.6.2"
+fontdue = "0.6.2"
+
+# The core APIs, including the Serialize and Deserialize traits. Always
+# required when using Serde. The "derive" feature is only required when
+# using #[derive(Serialize, Deserialize)] to make Serde work with structs
+# and enums defined in your crate.
+serde = { version = "1.0", features = ["derive"] }
+
+# Each data format lives in its own crate; the sample code below uses JSON
+# but you may be using a different one.
+serde_json = "1.0"