fix -f and -o clashing bug, and #6 #7

Author: asg017

bin/observable-prerender

@@ -83,10 +83,12 @@ program
       if (["png", "svg", "jpeg"].includes(outFileFormat)) {
         format = outFileFormat;
       } else {
-        console.error(
-          `Uknown file type "${outFileFormat}" passed in for --out parameter. Have the path end in .svg, .png, or .jpeg, or use the --format flag.`
-        );
-        process.exit(1);
+        if (!format) {
+          console.error(
+            `Unknown file type "${outFileFormat}" passed in for --out parameter. Have the path end in .svg, .png, or .jpeg, or use the --format flag.`
+          );
+          process.exit(1);
+        }
       }
     } else {
       if (!format) format = "svg";

bin/observable-prerender-animate

@@ -73,16 +73,18 @@ program
       redefine = [],
       redefineFile = [],
       fileAttachments = [],
-      format,
       iter,
       iterWaitfor = [],
       outDir,
       token,
-      width,
-      height,
       headless,
+      quiet,
     } = opts;
-    let { width, height, format } = opts;
+    let width, height, format;
+
+    width = opts.width;
+    height = opts.height;
+    format = opts.format;
 
     if (width) width = +width;
     if (height) height = +height;