fix: add validation when passing inline-images flag

src/cli.rs

@@ -164,7 +164,17 @@ impl<'a> TryFrom<ArgMatches<'a>> for AppConfig {
                     ExportType::EPUB
                 }
             })
-            .is_inlining_images(arg_matches.is_present("inline-images"))
+            .is_inlining_images(
+                (if arg_matches.is_present("inline-images") {
+                    if arg_matches.value_of("export") == Some("html") {
+                        Ok(true)
+                    } else {
+                        Err(Error::WrongExportInliningImages)
+                    }
+                } else {
+                    Ok(false)
+                })?,
+            )
             .try_init()
     }
 }

src/errors.rs

@@ -156,6 +156,8 @@ pub enum CliError<BuilderError: Debug + Display> {
     OutputDirectoryNotExists,
     #[error("Unable to start logger!\n{0}")]
     LogError(#[from] LogError),
-    #[error("The --inline-toc can only be used exporting to epub")]
+    #[error("The --inline-toc flag can only be used when exporting to epub")]
     WrongExportInliningToC,
+    #[error("The --inline-images flag can only be used when exporting to html")]
+    WrongExportInliningImages,
 }