feat: show ProcessMonitor loading errors

Normally missing qml modules like `QtWebSockets` are caught during widget initialization, but I am dynamically loading components depending on whether the optional C++ plugin is installed or not, and this way just throws a warning when the widget is added to a panel or when plasma starts.

Now these errors are shown on the widget.

refs: #29

Author: luisbocanegra

package/contents/ui/Cava.qml

@@ -26,10 +26,12 @@ Item {
     property bool idle
     property bool idleCheck
     property int idleTimer
-    property bool hasError: error !== ""
-    property string error
-    property bool usingFallback: process.usingFallback
-    property bool running: process.running
+    readonly property bool hasError: error !== ""
+    readonly property string error: process.stderr
+    readonly property list<string> loadingErrors: process.loadingErrors
+    readonly property bool loadingFailed: process.loadingFailed
+    readonly property bool usingFallback: process.usingFallback
+    readonly property bool running: process.running
     readonly property string cavaCommand: process.command
     readonly property string cavaConfig: {
         let config = `[general]
@@ -105,7 +107,7 @@ EOF
                 idleTimer.restart();
             }
         }
-        onStderrChanged: root.error = process.stderr
+        onLoadingErrorsChanged: root.error = process.loadingErrors.join("\n")
     }
 
     Timer {

package/contents/ui/CompactRepresentation.qml

@@ -86,7 +86,7 @@ Item {
         waveFillColorsCfg: root.waveFillColorsCfg
         values: cava.values
         debugMode: Plasmoid.configuration.debugMode
-        visible: !cava.hasError && !cava.idle
+        visible: !cava.hasError && !cava.idle && !cava.loadingFailed
     }
     Kirigami.Icon {
         anchors.centerIn: parent
@@ -96,7 +96,7 @@ Item {
         active: mouseArea.containsMouse
         isMask: true
         color: Kirigami.Theme.negativeTextColor
-        visible: cava.hasError
+        visible: cava.hasError || cava.loadingFailed
     }
 
     MouseArea {

package/contents/ui/FullRepresentation.qml

@@ -53,6 +53,9 @@ ColumnLayout {
                     if (cava.error) {
                         msg += `Error: ${cava.error}\n`;
                     }
+                    if (!cava.running && cava.loadingFailed) {
+                        msg += `Error: ${cava.loadingErrors.join('\n')}\n`;
+                    }
                     if (cava.running) {
                         msg += `CAVA is running\n`;
                     } else {

package/contents/ui/components/ProcessMonitor.qml

@@ -4,50 +4,54 @@ Item {
     id: root
 
     property string command: ""
-    property string stdout: ""
-    property string stderr: ""
-    property bool useFallback: false
-    property bool usingFallback: loader.source.toString() === "ProcessMonitorFallback.qml"
-    property bool running: false
+    readonly property string stdout: process.stdout ?? ""
+    readonly property string stderr: process.stderr ?? ""
+    readonly property bool forceFallback: false
+    readonly property bool running: process.running ?? false
+    property bool usingFallback: false
+    property var process: null
+    property bool loadingFailed: false
+    property list<string> loadingErrors
 
     function restart() {
-        if (loader.status === Loader.Ready) {
-            loader.item.restart();
+        if (process !== null) {
+            process.restart();
         }
     }
 
     function stop() {
-        if (loader.status === Loader.Ready) {
-            loader.item.stop();
+        if (process !== null) {
+            process.stop();
         }
     }
 
     onCommandChanged: {
-        if (loader.status === Loader.Ready) {
-            loader.item.command = root.command;
+        if (process !== null) {
+            process.command = root.command;
         }
     }
 
-    Loader {
-        id: loader
-
-        source: root.useFallback ? "ProcessMonitorFallback.qml" : "ProcessMonitorPrimary.qml"
-        onStatusChanged: {
-            if (status === Loader.Error) {
-                loader.source = "ProcessMonitorFallback.qml";
+    Component.onCompleted: {
+        let component = null;
+        const sources = ["ProcessMonitorFallback.qml"];
+        if (!root.forceFallback) {
+            sources.unshift("ProcessMonitorPrimary.qml");
+        }
+        for (let source of sources) {
+            component = Qt.createComponent(source);
+            if (component.status === Component.Ready) {
+                process = component.createObject(root);
+                process.command = root.command;
+                break;
+            } else {
+                console.warn(component.errorString());
+                root.loadingErrors.push(component.errorString());
             }
         }
-        onLoaded: {
-            loader.item.command = root.command;
-            loader.item.stdoutChanged.connect(() => {
-                root.stdout = loader.item.stdout;
-            });
-            loader.item.stderrChanged.connect(() => {
-                root.stderr = loader.item.stderr;
-            });
-            loader.item.runningChanged.connect(() => {
-                root.running = loader.item.running;
-            });
+
+        if (process === null) {
+            root.loadingFailed = true;
         }
+        root.usingFallback = component.url.toString().includes("ProcessMonitorFallback.qml");
     }
 }

package/contents/ui/main.qml

@@ -38,7 +38,7 @@ PlasmoidItem {
         if (Plasmoid.status === PlasmaCore.Types.RequiresAttentionStatus) {
             return;
         }
-        Plasmoid.status = (hideWhenIdle && cava.idle || !cava.running) && !Plasmoid.expanded && !editMode && !cava.hasError ? PlasmaCore.Types.HiddenStatus : PlasmaCore.Types.ActiveStatus;
+        Plasmoid.status = hideWhenIdle && (cava.idle || !cava.running) && !Plasmoid.expanded && !editMode && !cava.hasError ? PlasmaCore.Types.HiddenStatus : PlasmaCore.Types.ActiveStatus;
     }
     onExpandedChanged: {
         Utils.delay(1000, updateStatus, main);