fix never picking halfblocks

When no capabilities at all could be queried (including missing
fontsize), which is likely for terminals that don't support any graphics
protocol, then resort to halfblocks with some arbitrary font size in 1:2
ratio.

It's not super important to get those halfblocks images to show with the
same size as their pixel counterpart. Also some terminals scale graphics
by DPI and some don't, so there is no uniform scale anyway.

src/picker.rs

@@ -80,26 +80,37 @@ impl Picker {
         let (is_tmux, tmux_proto) = detect_tmux_and_outer_protocol_from_env();
 
         // Write and read to stdin to query protocol capabilities and font-size.
-        let (capability_proto, font_size) = query_with_timeout(is_tmux, Duration::from_secs(1))?;
-
-        // If some env var says that we should try iTerm2, then disregard protocol-from-capabilities.
-        let iterm2_proto = iterm2_from_env();
-
-        let protocol_type = tmux_proto
-            .or(iterm2_proto)
-            .or(capability_proto)
-            .unwrap_or(ProtocolType::Halfblocks);
-
-        if let Some(font_size) = font_size {
-            Ok(Picker {
-                font_size,
+        match query_with_timeout(is_tmux, Duration::from_secs(1)) {
+            Ok((capability_proto, font_size)) => {
+                // If some env var says that we should try iTerm2, then disregard protocol-from-capabilities.
+                let iterm2_proto = iterm2_from_env();
+
+                let protocol_type = tmux_proto
+                    .or(iterm2_proto)
+                    .or(capability_proto)
+                    .unwrap_or(ProtocolType::Halfblocks);
+
+                if let Some(font_size) = font_size {
+                    Ok(Picker {
+                        font_size,
+                        background_color: DEFAULT_BACKGROUND,
+                        protocol_type,
+                        is_tmux,
+                        kitty_counter: rand::random(),
+                    })
+                } else {
+                    Err(Errors::NoFontSize)
+                }
+            }
+            Err(Errors::NoCap) => Ok(Picker {
+                // This is completely arbitrary, but it doesn't matter much for halfblocks.
+                font_size: (4, 8),
                 background_color: DEFAULT_BACKGROUND,
-                protocol_type,
+                protocol_type: ProtocolType::Halfblocks,
                 is_tmux,
                 kitty_counter: rand::random(),
-            })
-        } else {
-            Err(Errors::NoFontSize)
+            }),
+            Err(err) => Err(err),
         }
     }
 
@@ -429,13 +440,13 @@ fn query_with_timeout(
     thread::spawn(move || {
         let _ = tx.send(
             enable_raw_mode()
+                .map_err(Errors::into)
                 .and_then(|disable_raw_mode| {
                     let result = query_stdio_capabilities(is_tmux);
                     // Always try to return to raw_mode.
                     disable_raw_mode()?;
                     result
-                })
-                .map_err(|dyn_err| io::Error::new(io::ErrorKind::Other, dyn_err.to_string())),
+                }),
         );
     });